Automotive terms Modern (R)

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms recommended for general use worldwide.For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

RACE:
The surface on the inner or outer ring of a bearing on which the balls, needles or rollers move.

RACK AND PINION:
A type of automotive steering system using a pinion gear attached to the end of the steering shaft. The pinion meshes with a long rack attached to the steering linkage.

RADIAL TIRE:
Tire design which uses body cords running at right angles to the center line of the tire, Two or more belts are used to give tread strength.Radials can be identified by their characteristic sidewall bulge.

RADIATOR:
Part of the cooling system for a water-cooled engine, mounted in the front of the vehicle and connected to the engine with rubber hoses, Through the radiator, excess combustion heat is dissipated into the atmosphere through forced convection using a water and glycol based mixture that circulates through, and cools, the engine,

RANGE REFERENCE AND CLUTCH/BAND APPLY CHART:
A guide that shows the application of clutches and bands for each gear, within the selector range positions. These charts are extremely useful for understanding how the unit operates and for diagnosing malfunctions.

RAVIGNEAUX GEARSET:
A compound planetary gearset that features matched dual planetary pinions (sets of two) mounted in a single planet
carrier. Two sun gears and one ring mesh with the carrier pinions.

REACTION MEMBER:
The stationary planetary member, in a planetary gearset, that is grounded to the transmission/transaxle case through the use of friction and wedging devices known as bands, disc clutches, and one-way clutches.

REACTION PRESSURE:
The fluid pressure that moves a spool valve against an opposing force or forces; the area on which the opposing force acts. The opposing force can be a spring or a combination of spring force and auxiliary hydraulic force.

REACTOR, TORQUE CONVERTER:
The reaction member of a fluid torque converter, more commonly called a stator. (See stator.)

REAR MAIN OIL SEAL:
A synthetic or rope-type seal that prevents oil from leaking out of the engine past the rear main crankshaft bearing.

RECIRCULATING BALL:
Type of steering system in which recirculating steel balls occupy the area between the nut and worm wheel, causing a reduction in friction.

RECTIFIER:
A device (used primarily in alternators) that permits electrical current to flow in one direction only.

REDUCTION:
(See gear reduction.)

REGULATOR VALVE:
A valve that changes the pressure of the oil in a hydraulic circuit as the oil passes through the valve by bleeding off (or exhausting) some of the volume of oil supplied to the valve.

REFRIGERANT 12 (R-12) or 134 (R-134):
The generic name of the refrigerant used in automotive air conditioning systems.

REGULATOR:
A device which maintains the amperage and/or voltage levels of a circuit at predetermined values.

RELAY:
A switch which automatically opens and/or closes a circuit.

RELAY VALVE:
A valve that directs flow and pressure. Relay valves simply connect or disconnect interrelated passages without restricting the fluid flow or changing the pressure.

RELIEF VALVE:
A spring-loaded, pressure-operated valve that limits oil pressure buildup in a hydraulic circuit to a predetermined maximum value.

RELUCTOR:
A wheel that rotates inside the distributor and triggers the release of voltage in an electronic ignition.

RESERVOIR:
The storage area for fluid in a hydraulic system; often called a sump.

RESIN:
A liquid plastic used in body work.

RESIDUAL MAGNETISM:
The magnetic strength stored in a material after a magnetizing field has been removed.

RESISTANCE:
The opposition to the flow of current through a circuit or electrical device, and is measured in ohms. Resistance is equal to the voltage divided by the amperage.

RESISTOR SPARK PLUG:
A spark plug using a resistor to shorten the spark duration. This suppresses radio interference and lengthens plug life.

RESISTOR:
A device, usually made of wire, which offers a preset amount of resistance in an electrical circuit.

RESULTANT FORCE:
The single effective directional thrust of the fluid force on the turbine produced by the vortex and rotary forces acting in different planes.

RETARD:
Set the ignition timing so that spark occurs later (fewer degrees before TDC).

RHEOSTAT:
A device for regulating a current by means of a variable resistance.

RING GEAR:
The name given to a ring-shaped gear attached to a differential case, or affixed to a flywheel or as part of a planetary gear set.

ROADLOAD:
grade.

ROCKER ARM:
A lever which rotates around a shaft pushing down (opening) the valve with an end when the other end is pushed up by the pushrod. Spring pressure will later close the valve.

ROCKER PANEL:
The body panel below the doors between the wheel
opening.

ROLLER BEARING:
A bearing made up of hardened inner and outer races between which hardened steel rollers move.

ROLLER CLUTCH:
A type of one-way clutch design using rollers and springs mounted within an inner and outer cam race assembly.

ROTARY FLOW:
The path of the fluid trapped between the blades of the members as they revolve with the rotation of the torque converter cover (rotational inertia), ROTOR: (1,) The disc-shaped part of a disc brake assembly, upon which
the brake pads bear; also called, brake disc. (2.) The device mounted atop the distributor shaft, which passes current to the distributor cap tower contacts.

ROTARY ENGINE:
see wankel engine.

RPM:
Revolutions per minute (usually indicates engine speed).

RTV:
A gasket making compound that cures as it is exposed to the atmosphere. It is used between surfaces that are not perfectly machined to one another, leaving a slight gap that the RTV fills and in which it hardens. The letters RTV represent room temperature vulcanizing.

RUN-ON:
Condition when the engine continues to run, even when the key is turned off. See dieseling.